diff --git a/hbase-common/src/main/java/org/apache/hadoop/hbase/types/CopyOnWriteArrayMap.java b/hbase-common/src/main/java/org/apache/hadoop/hbase/types/CopyOnWriteArrayMap.java
index bc184b1098a..1b9ea09f31d 100644
--- a/hbase-common/src/main/java/org/apache/hadoop/hbase/types/CopyOnWriteArrayMap.java
+++ b/hbase-common/src/main/java/org/apache/hadoop/hbase/types/CopyOnWriteArrayMap.java
@@ -332,7 +332,8 @@ public class CopyOnWriteArrayMap<K, V> extends AbstractMap<K, V>
     if (index < 0) {
       COWEntry<K, V> newEntry = new COWEntry<>(key, value);
       this.holder = current.insert(-(index + 1), newEntry);
-      return value;
+      // putIfAbsent contract requires returning null if no previous entry exists
+      return null;
     }
     return current.entries[index].getValue();
   }
diff --git a/hbase-common/src/test/java/org/apache/hadoop/hbase/types/TestCopyOnWriteMaps.java b/hbase-common/src/test/java/org/apache/hadoop/hbase/types/TestCopyOnWriteMaps.java
index 7c8a7d2f4b6..5487997afea 100644
--- a/hbase-common/src/test/java/org/apache/hadoop/hbase/types/TestCopyOnWriteMaps.java
+++ b/hbase-common/src/test/java/org/apache/hadoop/hbase/types/TestCopyOnWriteMaps.java
@@ -41,6 +41,7 @@ public class TestCopyOnWriteMaps {
   public static final HBaseClassTestRule CLASS_RULE =
     HBaseClassTestRule.forClass(TestCopyOnWriteMaps.class);
 
+  private static final int MAX_INITIAL_ENTRIES = 10_000;
   private static final int MAX_RAND = 10 * 1000 * 1000;
   private ConcurrentNavigableMap<Long, Long> m;
   private ConcurrentSkipListMap<Long, Long> csm;
@@ -50,7 +51,7 @@ public class TestCopyOnWriteMaps {
     m = new CopyOnWriteArrayMap<>();
     csm = new ConcurrentSkipListMap<>();
 
-    for (long i = 0; i < 10000; i++) {
+    for (long i = 0; i < MAX_INITIAL_ENTRIES; i++) {
       long o = ThreadLocalRandom.current().nextLong(MAX_RAND);
       m.put(i, o);
       csm.put(i, o);
@@ -60,6 +61,18 @@ public class TestCopyOnWriteMaps {
     csm.put(0L, o);
   }
 
+  @Test
+  public void testPutIfAbsent() {
+    long key = MAX_INITIAL_ENTRIES * 2;
+    long val = ThreadLocalRandom.current().nextLong(MAX_RAND);
+    // initial call should return null, then should return previous value
+    assertNull(m.putIfAbsent(key, val));
+    assertEquals(val, (long) m.putIfAbsent(key, val * 2));
+    // test same with csm so we ensure similar semantics
+    assertNull(csm.putIfAbsent(key, val));
+    assertEquals(val, (long) csm.putIfAbsent(key, val * 2));
+  }
+
   @Test
   public void testSize() {
     assertEquals("Size should always be equal", m.size(), csm.size());